This week, I sat down with PEOPLE to answer some of those questions and share secrets to Megan's fit pregnancy and killer post-baby body.

How did Megan stay healthy throughout her pregnancy?We worked out throughout her entire pregnancy. She was a model of health through the whole process. She really educated herself big time and had a great relationship with her physician so she really understood the safe boundaries of how to exercise and eat well during pregnancy. As a result, she knew how active she could be and she was very consistent and didn't overdo it.

As she progressed from trimester to trimester, we'd modify things. As a result, she was so fit at the point of delivery that it actually went more easily and she was able to get medical clearance relatively quickly to come back and keep working out.

How long after giving birth did she start working out?Definitely within a few weeks she was able to come back and workout. We didn't start at full speed – we eased into it.

How did she train post-baby?We used the exact same exercises as we did pre-baby. We just focused more on the process and adjusted our program to suit her specific needs and limitations. The workouts we did are like all of my other Five Factor workouts. They are five phases: a minimum five minute cardio warm-up, a lower body sculpting exercise, an upper body toning exercise, then an abdominal sculpting exercise, and finally, a five minute cool down. We tried to have her do minimal impact. Post-baby there shouldn't be a lot of jumping up and down.

A Sample Workout

Warm-up: Five minutes on the bike or treadmill

Lower Body: Skater lungeCross your right leg behind your left leg as you bend your left knee into a half-squat position. Extend your left arm out to the side and swing your right arm across your hips. Hop a few feet directly to the right, switching the position of your legs and arms. Repeat on opposite side.

Upper Body: Supine (lying down) triceps extensionLie face up on a bench with your arms raised straight above you, a weight in each hand; slowly lower them to the sides of your forehead and repeat.

Abdominal Sculpting: SupermanLay on your stomach with your legs and arms fully extended. Slowly, contract your lower back and raise your legs and arms off the ground. Then lower them back down.

Cool-down: Five minutes on stationary bike.

We do 20 repetitions of each upper body, lower body, and abs and cycle through those three exercises non-stop, repeating that circuit four times. Each day of the week she would come in and we'd do different body parts at least three days a week.

Post-baby, which is more important, exercise or diet?What's more important in a car, the gas or the tires? You need both. Megan and Brian eat really well. They both cook and love using their blender. They love my smoothie recipes! Megan's favorite is the red smoothie, which is whatever berries are in season, Chai tea, a scoop of protein powder and little bit of almond milk.

Check back every Wednesday for more insider tips from celebrity trainer Harley Pasternak on Hollywood's hottest bodies – and learn how to get one yourself! Plus: follow Harley on Twitter at @harleypasternak